Hi uma,
There are no expenses that you can claim for food, simply because we all need to eat, to survive. The other areas of your question cannot be answered in this forum.
Guidance on IR35 can be found at
Understanding off-payroll working (IR35).
For advice in these areas, you would need to contact our self assesment helpline on 0300 200 3310, contact our webchat facility at
Contact HMRC or seek professional advice.
Thank you.